DRAFT B - August 2020
© NEI 2020. All rights reserved. nei.org 33 Appendix B Assurance Case Development The assurance case structure provided in this appendix was adopted from IEEE 15016-2. The assurance case starts with a top-level claim for the system and uses a structured argument and evidence to support the claim. Through multiple levels of subordinate claims, the structured argument connects the top-level claim to the evidence. The assurance case is constructed
by connecting key elements, which include
•
Claims which
are assertions about a property of the system. Claims that are asserted as true without justification become assumptions and claims supporting the argument are called sub- claims.
•
Arguments which
link the evidence to the claim, which can be deterministic, probabilistic or qualitative.
•
Evidence which
provides the basis for the justification of the claim. Some sources of evidence
may include the design, the development process, testing, and inspections. A simplified diagram of an assurance case is shown in Figure B.
Top ClaimSub-claim 2
Supports
Is
evidence forEvidence
Argument
Supports
Sub-claim 1
Supports
Evidence
Argument
Supports
Is evidence for
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